This invention relates to magnetic recording media and in particular to the layered structure of the magnetic recording media.
There are many different forms of mass data storage technology used in modern computing. One of the prevailing forms of data recording is magnetic data recording due to its large capacity and re-usable recording media. Magnetic data recording may be implemented utilizing different types of magnetic recording media, including tapes, hard disks, floppy disks, etc. There is an ever increasing need for magnetic recording media with higher storage capacity, lower noise, and lower costs.
The structure of a typical thin film magnetic recording disk is multilayered and includes a substrate at its base covered by one or more layers of thin film followed by a magnetic layer and optionally another layer on top of the magnetic layer. The magnetic layer may be coated with an overcoat and/or an organic lubricant. The magnetic layer is the main body on which the magnetic bits are recorded.
Magnetic recording media can be longitudinal magnetic recording media or, more recently, perpendicular magnetic recording media. Perpendicular recording media have many advantages over longitudinal recording media and are currently the more preferred magnetic recording media.
The composition of a magnetic layer can vary but can include such compounds as FePt or CoPt as described, for example, in US Patent Appln, Publication US2004/0191578 to Chen et al. The quality of the magnetic layer is in part determined by the layer or layers between the substrate and the magnetic layer. Important magnetic properties, for example, coercivity which are crucial to the recording performance of a disk can depend primarily on the microstructure of the various thin film layers.
A seedlayer disposed between a substrate and an underlayer is described in Lee et al. in U.S. Pat. No. 5,800,931. The seedlayer described in Lee et al. is a MgO sputter deposited thin film. An underlayer having chromium, a chromium alloy or a material having a B2 ordered crystalline structure is then placed on the seedlayer prior to forming the magnetic layer. Formation of a seedlayer using MgO can lead to slow process times in production. High quality crystals of MgO, which are crucial for an optimal magnetic recording medium, are difficult to obtain and can also lengthen the processing time in production.